EuFe2_2As2_2 under high pressure: an antiferromagnetic bulk superconductor

We report the ac magnetic susceptibility $\chi_{ac}$ and resistivity $\rho$ measurements of EuFe$_2$As$_2$ under high pressure $P$. By observing nearly 100% superconducting shielding and zero resistivity at $P$ = 28 kbar, we establish that $P$-induced superconductivity occurs at $T_c \sim$~30 K in EuFe$_2$As$_2$. $\rho$ shows an anomalous nearly linear temperature dependence from room temperature down to $T_c$ at the same $P$. $\chi_{ac}$ indicates that an antiferromagnetic order of Eu$^{2+}$ moments with $T_N \sim$~20 K persists in the superconducting phase. The temperature dependence of the upper critical field is also determined.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78 No.

Childhood Depression, Interpersonal Problem-Solving, and Self-Ratings of Performance

This study investigated the application of interpersonal and cognitive theories of adult depression to childhood depression. The Childhood Depression Inventory was administered to elementary school children, aged nine to eleven. Those scoring in the upper and lower third of the sample were designated as depressed (n = 20) and nondepressed (n = 20). Within two days, a measure of interpersonal problem‐solving ability, three questionnaire items assessing self‐ratings of interpersonal problem‐solving performance, and the vocabulary subtest of the WISC‐R were administered to the depressed and nondepressed subjects. Consistent with interpersonal and cognitive theories, depressed children showed poorer primary means‐ends problem‐solving performance and lower self‐ratings on items assessing social‐comparison and self‐satisfaction with interpersonal problem‐solving performance. Depressed children also scored significantly lower on the vocabulary subtest. These findings are discussed in terms of their similarity to the responses of depressed adult subjects and their implications for further research examining childhood depression

LFU-K: An Effective Buffer Management Replacement Algorithm

Abstract. This paper introduces a new approach to database disk buffering, called the LFU-K method. The LFU-K page replacement algorithm is an im-provement to the Least Frequently Used (LFU) algorithm. The paper proposes a theoretical-probability model for formal description of LFU-K algorithm. Us-ing this model we evaluate estimations for the LFU-K parameters. This paper also describes an implementation of LFU-2 policy. As we demonstrate by trace-driven simulation experiments, the LFU-2 algorithm provides significant improvement over conventional buffering algorithms for the shared-nothing da-tabase systems.

A Comparison of Dipterans from Ten Created and Ten Natural Wetlands

This study compares densities of common larval dipterans collected from areas dominated by Pontederia cordata in 10 natural and 10 created freshwater herbaceous wetlands in central Florida. At each wetland, 7 core. samples were collected from each of 5 stations during summer 1993. In addition, stem densities, vegetation areal coverage, pH, dissolved oxygen, water temperature, water depth, conductivity, sediment quality, and leaf litter were measured at 3 locations near each of the 5 stations in each wetland. Of the 57 dipteran taxa collected, 20 occurred with sufficient abundance to justify statistical comparison. Despite a large sampling effort, there were no significant differences in densities of 20 commonly occurring taxa found in created and natural wetlands after considering the effect of multiple univariate tests. Comparison of environmental variables showed significant differences in stem densities for vegetation other than P. cordata,, pH, conductivity, and sediment quality. Canonical correspondence analysis, used to relate environmental and biological variables, suggests that pH, conductivity, and sediment quality are only weakly related to dipteran community structure. Despite differences in environmental conditions, there is no convincing evidence of differences in natural and created wetland dipteran communities